Metal tube for pyrolysis reaction

Abstract

A metal tube in the present invention is a metal tube for pyrolysis reaction with superior characteristics of both the heat exchange and the pyrolysis reaction, which is suitable for use in a process in which hydrocarbons are pyrolytically decomposed. The tube is a metal tube for pyrolysis reaction consisting of 3 or 4 spiral ribs 1 provided on an inner surface which are inclined at 20 to 35 degrees to an axial direction of the metal tube, and characterized in that h/Di of 0.1 to 0.2 and h/w of 0.25 to 1.0 when a height of the rib 1 is defined as “h”, a width of the rib 1 at its bottom part is defined as “w” and an inner diameter of the tube at the bottom part is defined as “Di” in cross section of the spiral rib 1.

The invention claimed is: 
     
       1. A metal tube for pyrolysis reaction comprising 3 or 4 spiral ribs, which have 20 to 35 degrees inclination to an axial direction of the metal tube, provided on an inner surface of the metal tube; characterized in that h is 5.0 to 9.0 mm and h/w of 0.25 to 0.46 when a height of the each spiral rib is defined as “h” and a width of the each spiral rib at its bottom part is defined as “w” in cross section perpendicular to the tube axis, wherein a cross-section shape of each rib is an isosceles triangle and the spiral ribs are integrally-formed with a tube body by hot extrusion. 
     
     
       2. The metal tube for a pyrolysis reaction according to  claim 1 , characterized in that the metal tube is a tube which is used for a pyrolysis reaction process of hydrocarbons.